Powerful Pulleys

Broad Question

Does the amount of combination pulleys affect the force of a pull.

Specific Question

Will two, three, or four wheels on a combination pulley use the least amount of force to pull up a weight.

Variables

Independent Variable: Amount of pulleys
Dependent Variable: Amount of force

Variables That Need To Be Controlled: Amount of Weight, type of rope

Hypothesis

I think that the more wheels on a combination pulley the less amount of force you will need to pull the weight.

Graph of Hypothesis

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General Plan

Experimental Design

For my experimental design I am finding out if the amount of wheels in a combination pulley will affect the force of the pull. I will be testing the experiment in my basement.The only person involved in the experiment will be myself. My role in the experiment will to pull the pulley to see how much force I use in each pull. I will test each combination pulley three times and then average the results together. I will record the results directly onto a spreadsheet on a computer. For my experiment I will tie a spring scale to the rope I am pulling and then record the measurement on the spring scale once the weight is pulled up all the way.

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Background Research

References

Materials List

Materials:

1. Spreadsheet
2. Pencil
3. Spring Scale
4. Pulley
5. Rope
6. Weight
7. Myself

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Conclusion

The purpose of this experiment was to find out if the number of wheels in a combination pulley would affect the force of a pull. The results of my experiment was that 4 wheels took the least amount of force with the average pull being 4.6 N. The one wheel pulley took the most amount of force with 7.7N. I measured the force using a spring scale with incriments of Newtons. When I used two wheels the force was 5.9 N and when I used three wheels the force was 6.6 N. So as you can see from my experiment it seems as though the combination pulleys with an even number of wheels reduces the force of the pull. That is the results of my experiment.

Data Table

Amount of Wheels	Trial 1	Trial 2	Trial 3	Average
1 wheel	8 N	7.5 N	7.7 N	7.7 N
2 wheels	6 N	5.9 N	5.9 N	5.9 N
3 wheels	6.5 N	6.6 N	6.7 N	6.6 N
4 wheels	4.7 N	4.8 N	4.5 N	4.6 N

Graphs

Photo

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Discussion

My hypothesis was that think that the more wheels on a combination pulley the less amount of force will be needed to pull the weight attached to the pulley. My results do support my hypothesis. There is a relationship between the independent and dependent variables. This is because the Independent is the amount of pulleys and the dependent is the amount of force. Some patterns and trends that my data shows are the more wheels in a pulley the less amount of force you need to lift the weight. Also an even amount of wheels in a pulley works better at reducing the force of a pull. I think the test I did went smoothly with minor problems. I say this because I had to do a second test because in my first test the numbers were all the same because I was using too much weight. If I could improve my experiment I would use more combinations of pulleys. An example of this would be having all small wheels or all big wheels in a pulley. An interesting future study might invovle finding out if my theory of a combination pulley with an even number of wheels would decrease the amount of force neede to lift the weight attached to the pulley.